Method for smelting high-arsenic copper sulfide ore

ABSTRACT

Provided herein is a method for smelting high-arsenic copper sulfide concentrate, which comprises the steps of: mixing the high-arsenic copper sulfide concentrate with quartz sand and CaO-containing material to obtain a mixed material; mixing the mixed material with oxygen-containing reactant gas and heating for reaction to obtain matte, slag and SO 2 -containing flue gas. By the addition of CaO and SiO 2  in the smelting process, the concentrate material, the CaO and the SiO 2  are allowed to react in the furnace under high temperature. The arsenic sulfides in the concentrate are oxidized first and then chemically react with slagging flux CaO to enter the slag phase in the form of calcium-based compounds of arsenic, iron arsenates and etc., thus reducing the arsenic content in the copper matte.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of the priority to CN application No. 201610950115.6 titled “A method for smelting high-arsenic copper sulfide ore”, filed with the Chinese State Intellectual Property Office on Nov. 2, 2016, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a field of non-ferrous pyrometallurgy technology, and in particular to a method for smelting high-arsenic copper sulfide ore.

BACKGROUND OF THE INVENTION

Copper pyrometallurgy involves four processes: smelting, converting, anode refining and electrolytic refining. The smelting process is mainly to remove a substantial amount of sulfur and iron, and also to remove arsenic, antimony, bismuth, lead, zinc and other impurity elements as much as possible. In metal smelting process, slagging is a very important part, as it was, a copper-making process is a slagging process, in which more arsenic, antimony and other impurities enter the slag so that the impurity content of the matte is reduced, and the smelting slag must also has the features of good fluidity, easy separation from metal (matte) and so on.

With the depletion of resources, there are more and more lean ores, correspondingly, impurity content, especially arsenic content, is getting higher and higher, and when the arsenic content goes beyond the scope of process design, the arsenic content in the copper matte produced from smelting will rise, accordingly, the arsenic content in the anode copper will also rise, which will add to the pressure of electrolyte purification, and affect the quality of cathode copper in serious cases. Presently, the treatment of high arsenic ore is mainly through the blending of a small amount of high arsenic ore so that the arsenic content after blending falls within the scope of process design, which method is not suitable for large-scale treatment of high arsenic ore.

The flash smelting technology, as the world's most advanced technology having the largest processing capacity, accounts for more than 60% of the world's pyrometallurgical copper production, and is recognized as an “eating fine grain” smelting technology, which generally requires low concentration of impurities in copper concentrate, such as less than 0.3% of arsenic, otherwise the crude copper and anode copper produced would have high arsenic content and thus affect the electrolytic production. However, the currently available copper concentrates are generally hard to meet this design requirement, which results in an excessive arsenic content in anode copper and affects electrolytic production. How to develop a copper smelting technology capable of treating high-impurity, especially high-arsenic copper concentrate becomes an issue concerned by the current technicians.

SUMMARY OF THE INVENTION

In view of this, the technical problem to be solved by this invention is to provide a method for smelting high-arsenic copper sulfide concentrate. The smelting method provided by this invention can treat copper sulfide concentrate with high arsenic content, and the matte produced is of high grade and low arsenic content.

This invention provides a method for smelting high-arsenic copper sulfide concentrate, which comprises the steps of:

(A) mixing the high-arsenic copper sulfide concentrate with quartz sand and CaO-containing material to obtain a mixed material; and

(B) charging the mixed material and oxygen-containing reactant gas into a smelting furnace for reaction to obtain matte, slag and SO₂-containing flue gas.

Preferably, the step (B) is specifically as follows:

(B1) the mixed material is allowed to go through a conveying pipe (3) with inclination of 10° to 40° and enter a fluidizing feeding device (2), and then flow into a copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

(B2) the mixed material and the oxygen-containing reactant gas are mixed into a flash furnace reaction tower (4) under the action of the copper concentrate nozzle (1) and reacted therein to obtain matte, slag and SO₂-containing flue gas.

Preferably, the high-arsenic copper sulfide concentrate contains 0.3 wt % to 1.8 wt % of arsenic.

Preferably, the CaO-containing material is selected from the group consisting of quicklime, limestone or gypsum.

Preferably, the CaO-containing material is added in an amount of 1 wt % to 10 wt % based on the mass of the mixed material.

Preferably, the moisture content in the mixed material is less than 0.3 wt %.

Preferably, the oxygen content of the oxygen-containing reactant gas is 50% to 95%.

Preferably, the grade of the matte is 50% to 70%.

Preferably, the matte contains 0.2 wt % to 0.6 wt % of arsenic.

Compared with the prior art, the present invention provides a method for smelting high-arsenic copper sulfide concentrate, which comprises the steps of: mixing the high-arsenic copper sulfide concentrate with quartz sand and CaO-containing material to obtain a mixed material; and charging the mixed material and oxygen-containing reactant gas into a smelting furnace for reaction to obtain matte, slag and SO₂-containing flue gas. In the present invention, by the addition of CaO and SiO₂ in the smelting process, the concentrate material, the CaO and the SiO₂ are allowed to react in a high temperature state, the arsenic sulfides in the concentrate are oxidized first and then chemically react with slagging flux CaO to enter the slag phase in the form of calcium-based compounds of arsenic, iron arsenates and etc., thus reducing the arsenic content in the copper matte.

The results show that the matte produced by the smelting method of this invention has a grade of 50% to 70%, the matte contains 0.2 wt % to 0.6 wt % of arsenic, and the ratio of arsenic entering the slag is more than 70%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural view of a smelting device for high-arsenic copper sulfide concentrate according to the present invention.

In which, 1 is a copper concentrate nozzle, 2 is a vulcanization feeding device, 3 is a conveying pipe, and 4 is a flash furnace reaction tower.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention provides a method for smelting high-arsenic copper sulfide ore, which comprises the steps of:

mixing the high-arsenic copper sulfide concentrate with quartz sand and CaO-containing material to obtain a mixed material; and

mixing the mixed material with oxygen-containing reactant gas and heating for reaction to obtain matte, slag and SO₂-containing flue gas.

The copper sulfide concentrate provided in the present invention is high-arsenic copper sulfide concentrate. In the present invention, the high-arsenic copper sulfide concentrate contains 0.3 wt % to 1.8 wt %, preferably 0.4 wt % to 1.6 wt % of arsenic. In some specific embodiments of the present invention, the high-arsenic copper sulfide concentrate contains 0.4 wt % of arsenic. In some other specific embodiments of the present invention, the high-arsenic copper sulfide concentrate contains 0.6 wt % of arsenic. In some other specific embodiments of the present invention, the high-arsenic copper sulfide concentrate contains 0.8 wt % of arsenic. In some other specific embodiments of the present invention, the high-arsenic copper sulfide concentrate contains 1.0 wt % of arsenic. In some other specific embodiments of the present invention, the high-arsenic copper sulfide concentrate contains 1.6 wt % of arsenic.

In the present invention, the high-arsenic copper sulfide concentrate needs to be dried prior to smelting to a moisture content after drying of less than 0.3 wt %.

The dried high-arsenic copper sulfide concentrate, quartz sand and CaO-containing material are mixed to obtain a mixed material.

In order to reduce the amount of slag and to ensure a certain degree of impurity removal, a calcium oxide containing material selected from the group consisting of quicklime, limestone or gypsum is added during the smelting process of the copper sulfide ore.

The CaO-containing material is added in an amount of 1 wt % to 10 wt %, preferably 2 wt % to 8 wt %, more preferably 4 wt % to 6 wt % based on the mass of the mixed material.

The resulting mixed material has a moisture content of less than 0.3 wt %.

The mixed material and oxygen-containing reactant gas are charged into a smelting furnace and reacted therein to obtain matte, slag and SO₂-containing flue gas.

The smelting furnace for the smelting of high-arsenic copper sulfide concentrate according to the present invention is not particularly limited and may be any smelting furnace known to those skilled in the art, which could be a flash furnace or a bath furnace. The smelting time and smelting temperature in the smelting are chosen to match the equipment according to the variety of the chosen smelting equipment.

In the present invention, a smelting device having the structure of FIG. 1 is preferably used, and FIG. 1 is a schematic structural view of a smelting device for high-arsenic copper sulfide concentrate according to the present invention.

In FIG. 1, 1 is a copper concentrate nozzle, 2 is a fluidizing feeding device, 3 is a conveying pipe, and 4 is a flash furnace reaction tower.

The smelting device for high-arsenic copper sulfide concentrate according to the present invention mainly comprises a conveying pipe 3, a flash furnace reaction tower 4, a copper concentrate nozzle 1 which communicates with the conveying pipe 3 and the flash furnace reaction tower 4, and a fluidizing feeding device 2 provided at the portion where the copper concentrate nozzle 1 communicates with the conveying pipe 3.

As shown in FIG. 1, in this embodiment, the additional provision of the fluidizing feeding device 2 serves to allow the mixed material to more uniformly enter the material passage of the copper concentrate nozzle 1, and in turn more uniformly enter the reaction tower, thereby maximizing the prevention of segregation phenomenon and leading to a more prominent reaction effect.

After obtaining the mixed material, in the present invention, it is preferably to feed the mixed material to a smelting device having the structure of FIG. 1 to carry out smelting reaction.

(B1) The mixed material is allowed to go through the conveying pipe (3) with inclination of 10° to 40° and enter the fluidizing feeding device (2), and then flow into the copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

(B2) The mixed material and the oxygen-containing reactant gas are mixed into the flash furnace reaction tower (4) under the action of the copper concentrate nozzle (1) and reacted therein to obtain matte, slag and SO₂-containing flue gas.

Specifically, in the present invention, when flash smelting is adopted, the mixed material is allowed to go through the conveying pipe (3) with inclination of 10° to 40° and enter the fluidizing feeding device (2), and then flow uniformly into the copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2); at the same time, the oxygen-containing reactant gas enters the copper concentrate nozzle (1) through a pipeline; the mixed material and the oxygen-containing reactant gas enter the flash furnace reaction tower (4) under the action of the copper concentrate nozzle (1) to react and produce matte, slag and SO₂-containing flue gas.

In order to improve the flue gas concentration and reaction efficiency, as well as to ensure the heat balance of the reaction, in the smelting process, it is generally that the oxygen content of the oxygen-containing reactant gas is 50% to 95%, which is conducive to the oxidation of impurities in copper concentrate and the entering into the smelting slag, thus reducing the content of impurities in the matte. In the present invention, the oxygen content of the oxygen-containing reactant gas is 50% to 95%, preferably 60% to 90%, and more preferably 70% to 80%.

The mixed material and the reactant gas are further mixed in the smelting furnace reaction tower, and are decomposed and oxidized with the rising of the temperature before entering a sedimentation pool for slagging reaction to occur and generate matte, slag and SO₂-containing flue gas, wherein the matte and the slag enter the sedimentation pool at the bottom of the reaction tower for sedimentation and separation, and the SO₂-containing flue gas goes through the uptake flue of the smelting furnace for discharge. According to the above smelting method, the grade of the matte obtained is 50% to 70%. The matte contains 0.2 wt % to 0.6 wt % of arsenic.

The chemical reactions taking place in the smelting equipment are as follows:

Decomposition reactions:

2FeS₂→2FeS+S₂

4CuFeS₂→2Cu₂S+2FeS+S₂

CaCO₃→CaO+CO₂

Oxidation reactions:

4CuFeS₂+5O₂→2Cu₂S.FeS+2FeO+4SO₂

4FeS₂+11O₂→2Fe₂O₃+8SO₂

3FeS₂+8O₂→2Fe₃O₄+6SO₂

CuS+O₂→Cu₂S+SO₂

2Cu₂S+3O₂→2Cu₂O+2SO₂

2As₂S₂+7O₂→2As₂O₃+4SO₂

Matting reactions:

FeS+Cu₂O→FeO+Cu₂S

Slagging reactions:

2FeO+SiO₂→2FeO.SiO₂

As₂O₃+3CaO+O₂→Ca₃(AsO₄)₂

By the addition of CaO and SiO₂ in the smelting process, the concentrate material, the CaO and the SiO₂ are allowed to react in the furnace under high temperature. The arsenic sulfides in the concentrate are oxidized first and then chemically react with slagging flux CaO to enter the slag phase in the form of calcium-based compounds of arsenic, iron arsenates and etc., thus reducing the arsenic content in the copper matte.

The high-arsenic copper sulfide ore contains Fe element. In this invention, at the time of preparing the material for the furnace, quartz sand is added in an amount so that the ratio between the mass of Fe and the mass of SiO₂ is 1: (0.6-0.9), in this way, the FeO produced during the reaction forms slag and the reaction 2FeO+SiO₂→2FeO.SiO₂ occurs to ensure that the smelting slag is relatively low in viscosity and has good fluidity, which is conducive to the separation of smelting slag and copper matte and the reduction of copper content in the smelting slag. By controlling the ratio of Fe/SiO₂ in the slag, the overall fluidity of the slag is adjusted so that it is favorable for the discharge.

The specific reactions are as follows:

CaCO₃→CaO+CO₂

2As₂S₂+7O₂→2As₂O₃+4SO₂

As₂O₃+3CaO+O₂→Ca₃(AsO₄)₂

In addition, a small amount of As₂O₃ may react with the Fe₂O₃ generated from the concentrate oxidation and form iron arsenate. The reaction is as follows:

As₂O₃+3Fe₂O₃+O₂→FeAsO₄

The smelting method according to the present invention is capable of treating copper concentrate with arsenic content of 0.3% to 1.8%, and the matte produced contains less than 0.4% of arsenic; in addition, the slag obtained has good fluidity, the copper content in the slag is stable and low; this smelting method has large capacity of treating high-arsenic copper sulfide ore and is suitable for large-scale industrial production.

The results show that the matte produced by the smelting method of this invention has a grade of 50% to 70%, the matte contains 0.2 wt % to 0.6 wt % of arsenic, and the ratio of arsenic entering the slag is more than 70%.

In order to further understand the present invention, the method for smelting high-arsenic copper sulfide ore according to this invention will be described below with reference to Examples, and the scope of the present invention is not limited by the following examples.

EXAMPLE 1

100 tons of copper sulfide concentrate containing 0.4% of arsenic, blended in which 18 tons of quartz sand and 2.5 tons of quicklime powder were mixed to obtain mixed material, the mixed material was allowed to go through conveying pipe (3) with inclination of 15° and enter fluidizing feeding device (2), and then flow into copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

The mixed material and oxygen-rich reactant gas with oxygen concentration of 80% were mixed together under the action of the copper concentrate nozzle (1) into flash furnace reaction tower at a temperature of 1280° C., where they began decomposition and oxidation reactions with the rising of the temperature of the mixed material and the reactant gas, and finally went into the sedimentation pool at the bottom, which process produced matte of 36.7 tons, as well as slag and SO₂-containing flue gas. The matte contained 68% of Cu, 0.25% of As, and the ratio of arsenic entering the slag was 71.2%.

EXAMPLE 2

100 tons of copper sulfide concentrate containing 0.6% of arsenic, blended in which 16 tons of quartz sand and 4 tons of quicklime powder were mixed to obtain mixed material, the mixed material was allowed to go through conveying pipe (3) with inclination of 20° and enter fluidizing feeding device (2), and then flow into copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

The mixed material and oxygen-rich reactant gas with oxygen concentration of 86% were mixed together under the action of the copper concentrate nozzle (1) into flash furnace reaction tower at a temperature of 1300° C., where they began decomposition and oxidation reactions with the rising of the temperature of the mixed material and the reactant gas, and finally went into the sedimentation pool at the bottom, which process produced matte of 35.7 tons, as well as slag and SO₂-containing flue gas. The matte contained 67.2% of Cu, 0.32% of As, and the ratio of arsenic entering the slag was 77.9%.

EXAMPLE 3

100 tons of copper sulfide concentrate containing 0.8% of arsenic, blended in which 17 tons of quartz sand and 6 tons of quicklime powder were mixed to obtain mixed material, the mixed material was allowed to go through conveying pipe (3) with inclination of 30° and enter fluidizing feeding device (2), and then flow into copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

The mixed material and oxygen-rich reactant gas with oxygen concentration of 84% were allowed to enter together into flash furnace reaction tower at a temperature of 1300° C., where they began decomposition and oxidation reactions with the rising of the temperature of the mixed material and the reactant gas, and finally went into the sedimentation pool at the bottom, which process produced matte of 36 tons, as well as slag and SO₂-containing flue gas. The matte contained 65.2% of Cu, 0.38% of As, and the ratio of arsenic entering the slag was 70.2%.

EXAMPLE 4

100 tons of copper sulfide concentrate containing 0.4% of arsenic, blended in which 18 tons of quartz sand, 2.5 tons of quicklime powder and a small amount of soot were mixed to obtain mixed material, the mixed material was allowed to go through conveying pipe (3) with inclination of 35° and enter fluidizing feeding device (2), and then flow into copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

The mixed material and oxygen-rich reactant gas with oxygen concentration of 80% were allowed to enter together into flash furnace reaction tower at a temperature of 1260° C., where they began decomposition and oxidation reactions with the rising of the temperature of the mixed material and the reactant gas, and finally went into the sedimentation pool at the bottom, which process produced matte of 36.7 tons, as well as slag and SO₂-containing flue gas. The matte contained 68% of Cu, 0.25% of As, and the ratio of arsenic entering the slag was 71.2%.

EXAMPLE 5

100 tons of copper sulfide concentrate containing 0.6% of arsenic, blended in which 16 tons of quartz sand, 4.5 tons of quicklime powder and a small amount of soot were mixed to obtain mixed material, the mixed material was allowed to go through conveying pipe (3) with inclination of 30° and enter fluidizing feeding device (2), and then flow into copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

The mixed material and oxygen-rich reactant gas with oxygen concentration of 58% were allowed to enter together into flash furnace reaction tower at a temperature of 1300° C., where they began decomposition and oxidation reactions with the rising of the temperature of the mixed material and the reactant gas, and finally went into the sedimentation pool at the bottom, which process produced matte of 35.7 tons, as well as slag and SO₂-containing flue gas. The matte contained 67.2% of Cu, 0.29% of As, and the ratio of arsenic entering the slag was 77.9%.

EXAMPLE 6

100 tons of copper sulfide concentrate containing 1% of arsenic, blended in which 17 tons of quartz sand, 7.5 tons of quicklime powder and a small amount of soot were mixed to obtain mixed material, the mixed material was allowed to go through conveying pipe (3) with inclination of 25° and enter fluidizing feeding device (2), and then flow into copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

The mixed material and oxygen-rich reactant gas with oxygen concentration of 88% were allowed to enter together into flash furnace reaction tower at a temperature of 1240° C., where they began decomposition and oxidation reactions with the rising of the temperature of the mixed material and the reactant gas, and finally went into the sedimentation pool at the bottom, which process produced matte of 36 tons, as well as slag and SO₂-containing flue gas. The matte contained 65.2% of Cu, 0.33% of As, and the ratio of arsenic entering the slag was 79.2%.

EXAMPLE 7

100 tons of copper sulfide concentrate containing 1.6% of arsenic, blended in which 15.5 tons of quartz sand and 9.5 tons of quicklime powder were mixed to obtain mixed material, the mixed material was allowed to go through conveying pipe (3) with inclination of 40° and enter fluidizing feeding device (2), and then flow into copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2);

The mixed material and oxygen-rich reactant gas with oxygen concentration of 95% were allowed to enter together into flash furnace reaction tower at a temperature of 1250° C., where they began decomposition and oxidation reactions with the rising of the temperature of the mixed material and the reactant gas, and finally went into the sedimentation pool at the bottom, which process produced matte of 36 tons, as well as slag and SO₂-containing flue gas. The matte contained 68% of Cu, 0.43% of As, and the ratio of arsenic entering the slag was 84.7%.

While the preferred embodiments of the present invention have been described hereinabove, it is to be noted that, various improvements and modifications thereof will be apparent to those skilled in the art without departing from the principle of the invention. All such improvements and modifications are intended to fall within the scope of the following claims. 

1. A method for smelting high-arsenic copper sulfide concentrate, comprising: (A) mixing the high-arsenic copper sulfide concentrate with quartz sand and CaO-containing material to obtain a mixed material; and (B) charging the mixed material and oxygen-containing reactant gas into a smelting furnace for reaction to obtain matte, slag and SO₂-containing flue gas.
 2. The smelting method according to claim 1, wherein the step (B) is performed as follows: (B1) the mixed material is allowed to go through a conveying pipe (3) with inclination of 10° to 40° and enter a fluidizing feeding device (2), and then flow into a copper concentrate nozzle (1) under the fluidization action of the fluidizing feeding device (2); (B2) the mixed material and the oxygen-containing reactant gas are mixed into a flash furnace reaction tower (4) under the action of the copper concentrate nozzle (1) and reacted therein to obtain matte, slag and SO₂-containing flue gas.
 3. The smelting method according to claim 1, wherein the high-arsenic copper sulfide concentrate contains 0.3 wt % to 1.8 wt % of arsenic.
 4. The smelting method according to claim 1, wherein the CaO-containing material is selected from the group consisting of quicklime, limestone and gypsum.
 5. The smelting method according to claim 1, wherein the CaO-containing material is added in an amount of 1 wt % to 10 wt % based on the mass of the mixed material.
 6. The smelting method according to claim 1, wherein the moisture content in the mixed material is less than 0.3 wt %.
 7. The smelting method according to claim 1, wherein the oxygen content of the said oxygen-containing reactant gas is 50% to 95%.
 8. The smelting method according to claim 1, wherein the grade of the matte is 50% to 70%.
 9. The smelting method according to claim 1, wherein the matte contains 0.2 wt % to 0.6 wt % of arsenic. 